israel



C. S. MCDOWELL AND L. L. ISRAEL. OPTICAL SIGNALING APPARATUS. APPLICATION FILED JAN. 7, 1916.

Patented July 8, 1919.

INVENTORS $51M: DOW-ELL L.L. ISRAE ATTORNE UNITED STATES PATENT OFFICE.

CLYDE S. MODOWELL, OF THE UNITED STATES NAVY, AND LESTER L. ISRAEL, OF NEW YORK, N. Y., ASSIGNORS TO THE SPERRY GYROSCOPE COMPANY, OF BROOKLYN, NEW

YORK, A CORPORATION OF NEW YORK.

LSOQAQL Specification of Letters Patent.

OPTICAL SIGNALING ALPPABATUS.

Patented July 8, 1919.

Application filed January 7, 1915. Serial No. 70,741.

- l States, stationed on U. S. S. Golwmbz'a and the countyv residing at New York city, in of New York and State of New York, re-

spectively, have invented certain new and "useful Improvements in Optical Signaling Apparatus, of which the following is aspecification.

This invention relates to means fortransmitting signals over comparatively longdis- Y tances es ecially in daylight. While the system 0? flashing or blinking lights has been used on ships for along time to transmit signals at night, no successful system has been devised for. optical signaling in daytime, The most successful method makes use of theifact that a Searchlight, if focused directly on an observer, canbe seen in the daytime, and at the same time is invisible from any other point. The present method of utilizing the Searchlight or signaling is to equip it with a shutter which can be rapidly opened and closed to produce dots and dashes of light, in the same way as is done with the blinker system above referred to, or in the Morse code.

The object of this invention is to render h unnecessary the vibratory shutter above referred to, and to increase the ra idity at which the signals may be sent. ferrlng to the drawings in which, what we now consider to be the preferred form of our invention, is shown: Fi re 1, is an'elementary wiring diagram i lustrating the essential principles of our invention. Fig. 2, is a more detailed wiring diagram showing the preferred construction of our invention.

While it is a simple problem to flash ordi= nary incandescent lights b simply breaking the circuit, a more d' cult problem is presented to flash arc lights in which merely closing the circuit after it has been broken will not reestablish the light, as is the case with incandescent lights, since as is well known, a much higher voltage is required to jump a spark gap, than is required to I maintain an are when established across the gap. Another dificulty is to quickly and effectively interrupt the heavy current used in large searchlights, which amounts in shown at (3 through the are light, and

method is very eifective in sending signals,

since although the arc is never entirely extinguished, a material variation in the brilliancy furnishes as reliable a signaling means as the blinking of the ordinary signaling light, and at the same time may be seen at a much greater distance. In the elementary wiring diagram, the main circuit is shown at (1) and the are light at (2). The usual Searchlight rheostat is An auxiliary resistance l) is adapted o be thrown into and out of circuit with the are by means of a switch (5), which, when closed, completes the short circuit around said resistance directly throws the resistance into series with the are light. This switch or key, may be operated directly by hand or indirectly as a relay as hereinafter explained-in connection with Fig. 2. To secure the best results, the contact points are preferably made exceed materially about mils.

A second switch (6) is shown adjacent switch (5) which is'adapted to be closed at the time switch ('5) is opened or shortly thereafter. an inductance large capacity. from a (7) and a condenser (8) of A circuit is also completed point of the main circuit beyond switch (5) to one plate (9) of the cons denser; the other plate (10) being connected through a resistance (11) to the return circuit. The purpose of the condenser in the conducting circuit is to quench the arc which would be drawn by the opening of the switch (5). This is accomplished as follows When switch (5) is closed, the plates (9) of the condenser are given a positive char and the plates (10) a negative charge. E: soon as the switch (5) opens, the switch (6) closes which completes a circuit around through condenser the arc across switch (5). It will at once be seen that; the condenser is now connected to discharge across gap (5) in the opposite greatly vary the brilliancy of when opened of silver and the opening should not In circuit with switch (6) is (8),*inductance (7) and indicated at (26) direction to the current then flowing across the gap. This surge of current from the con.- denser will immediately quench the arc, since the condenser is charged to practically the full line voltage, the are being extinguished as soon as the condenser discharge current becomes equal to the line current.

Referring to Fig. 2, it will be seen that the same system is here employed, but with several additions thereto. The main circuit is here shown at 1 numeral 110 denoting the generator. We prefer to use a small key (111) to transmit the signals which controls 'the circuit breaking key through a rela" magnet (12). Preferably two relays (13) and (14) in series are used to increase the reliability of operation, the one key (111) serving to operate both relays. Ma gnet (12 is arranged to attract against the tension of a spring (15) the pivoted armature (16) on which are mounted a pair of contacts (17) and (18). Contact (17) is normally in contact with point (19), these contacts corresponding to switch (5) of 1, so that the auxiliary resistance which is here shown at (26) is normally short circuited. On closing key (111), however, magnet (12) breaks contact (17) and: (19) and draws contact (18) against the contact (20), which parts correspond to switch (6) of Fig, 1. This, as before, throws resistance (26) into series with are 2, and completes a circuit around through the condensers.

In Fig. 2 the condensers are shown in one bank being.

two banks at (21) and (22), connected to each of the sets of switches and the corresponding inductances are shown at (28) and (24). The resistances which connect the condenser to one side of the main line are shown at (124) and (25) while the auxiliary resistance which and out of circuit with the Searchlight is If desired, a small condenser (28) may hand key (111) as shown. Preferably the relay switches are so constructed that they may be operated directly by hand instead of through key (111) as indicated by finger pieces (29) The values of the resistances, condensers,

etc., that are used will, of course, vary with the type of are employed, and with the speed at which it is desired to transmit the signals. Resistance (26) high enough to greatly diminish the brilliancy of the arc, and is preferably so designed that just enough current will pass through the arc to keep it burning when this resistance is in circuit. This minimum current is found to be about one-tenth of the normal arc current, so that the light produced thereby is practically invisible at a distance. The growth and decay of the intense arc light is practically simultaneous with the ch in the arc current, and there- .a ship, the master key is thrown into be connected around the quenching is, of course, made fore no perceptible time lag in sending occurs. The inductance and condensers are chosen so as to provide for a maximum surge current of several times the are current. The value of resistances (124i) and (25) may be varied, greatly, depending upon the speed at which the signals are to be sent, Thus a resistance of 800 ohms will only allow a sending speed of about 12 words a minute, whileif the resistance is decreased to 250 ohms, a speed of 30 words a minute may be reached, and even a greater transmission speed may be obtained by a further decrease in the value of this resistance.

Our invention may be easily applied to any form of searchlight.

(111) may be located in any convenient posit an and the remainder of the control apparatus including the relays, condensers, etc, may be installed in the base of the searchlight. The operation of the device is, of course, extremely simple, since all the signal oflicer need do is to operate key (111) in the same manner that a telegraph key is used.

In accordanc with the provisions of the patent statutes, we have herein described the principle of operation of our invention, together with the apparatus, which we now consider to represent the best embodiment thereof but we desire to have it understood that the apparatus is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

We claim- 1. An optical signalingsystem comprising an are light, means for varying the liancy thereof including a resistance, means for throwing said resistance into and out 0 series with the arc, said last named means including a manually controlled switch in parallel with said resistance, and means for the are across said switch.

2. In combination, an are light, a resistance in series therewith,- a switch in parallel with said resistance and means for reducing the arc-over across said switch.

3. In an optical signaling device, an are light, means adapted to vary the current passing throu h the arc, and means for controlling the action of said other means comprising a main circuit breaking switch, a condenser connected so as to charge when said switch is closed, and a second switch adapted to cause said condenser to discharge across said switch in an opposite'direction to the main circuit.

4. In an optical signaling device, an are light, means adapted to vary the current pasbrilsage through the arc, and means for controlling the action of said other means comprising a main circuit breaking switch, a second switch, a condenser connected so as to charge when said first switch is closed and said second switch is open, a master key and electromagnetic means governed by said key for operating both of said switches.

5. In combination, an are light, a resistance in series therewith, ashunt connection around said resistance, a switch in said shunt connection and means for impressing a counter-electro-motive-force across said switch.

6. In an optical signaling device, an are light, means adapted to vary the current passing through the arc for dimming the same, and means for controlling the action of said other'means comprising a main circuit breaking switch, a condenser connected so as to charge when said switch is closed, and a second switch adapted to cause said condenser to discharge across the first menfor extinguishing the are between the points of said switch when the latter is opened, said means comprising a condenser and connections for charging the condenser when said switch is closed and discharging the condenser when said switch is opened.

In testimony whereof we aifix our signatu-res.

CLYDE S. MCDOWELL. LESTER L. ISRAEL. 

